Make WallpaperMS bind wallpaper component PendingIntent immutable. am: 178da54fc9 am: 6ea3559233 am: 5b295c7726 am: b3fd083cb1 am: 254924da94 am: b180f6990a am: 89685e6612

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/12718925

Change-Id: I0ab2b7c3318fad0e8bbbab4b1f7ae9b0b874bba1